The present invention relates generally to package wrapping machines wherein packages to be wrapped are carried along a conveyor path extending between and including a feed-in station and a wrapping station and, more particularly, to a dropped-article sensor for catching an article dropped from the conveyor path and for generating a wrapping machine interrupt signal in response thereto.
A large variety of package wrapping machines are known in the prior art. One category of wrapping machine which is presently very popular in the supermarket industry includes a package elevator. In such machines, packages such as trayed meat, produce or other food products are initially placed at a feed-in station, conveyed from the feed-in station to a wrapping station including the elevator which then raises the packages into sheets of wrapping material. The sheets of wrapping material are then folded about the packages and secured therebeneath to attractively display the meat, produce or other food products. An illustrative package elevating wrapping machine which utilizes film wrapping material is disclosed in U.S. Pat. No. 4,501,106, issued to Fritz F. Treiber et al. on Feb. 26, 1985, and entitled "Wrapping Control System for Film Wrapping Machine," which patent is assigned to the assignee of the present application and is incorporated herein by reference. While the present invention is applicable to any wrapping machine wherein packages to be wrapped are conveyed from a feed-in station to a wrapping station, the dropped-article sensor of the present invention is particularly applicable to elevating wrapping machines and, hence, will be described herein with reference to such machines. The term "article" as used herein should be interpreted as referring to a package or a part or portion of a product making up a package. Two solutions to the problem of dropped articles have been utilized in known package elevating wrapping machines. In the first solution, a chute or slide is positioned adjacent to and inclined away from the elevator to catch and direct dropped articles toward the operator end of the machine. An operator may then open the machine to retrieve a dropped article and possibly salvage the article.
In the interest of saving space, package wrapping machines are preferably compact and include relatively dense construction of mechanical apparatus to perform the wrapping. See, for example, the above-referenced U.S. Pat. No. 4,501,106. Accordingly, articles which are inadvertently dropped to the article catching slide, particularly in the case of larger sized articles, may interfere with or be engaged by operating mechanisms within the wrapping machine. For example, in the wrapping machine of the above-referenced patent application, a package pusher is continuously circulated in close proximity to the article catching slide. If a dropped article remains on the slide, the package pusher may engage and jam the article, potentially damaging or jamming the machine and/or destroying the article.
In accordance with the second solution to the problem, a dropped-article catcher pan is coupled to an elevator of a package elevating wrapping machine to follow the reciprocating movement of the elevator and, hence, be ever-present and available for catching a dropped article. Such a dropped-article catcher pan is disclosed in U.S. patent application Ser. No. 578,146, filed by Glenn R. Stockmeier et al. on Feb. 8, 1984, and entitled "Dropped-Package Catcher," which application is assigned to the assignee of the present application and is incorporated herein by reference.
The dropped-article catcher pan overcomes the problem of the prior art chute or slide by catching one or a limited number of articles in the pan. However, problems may be encountered if operators of the wrapping machine fail to clean out the article catcher pan as articles are dropped. Oftentimes, the operators may be unaware that an article has fallen from the conveyor path. If the pan is not cleared each time one or a small number of articles are dropped, one or more articles remain in the tray and may soil the tray and lead to an unsanitary condition. Further, after a limited number of articles have been accumulated in the catcher pan, the next article to be dropped may lead to a machine jam requiring service personnel to restore the machine to operation. In addition, the dropped-article catcher pan as well as the preceding dropped-article chute or slide are difficult to clean or are "overlooked" by the machine operator, hence, leading to unsanitary surfaces. When an article falls on such an unsanitary surface, the article becomes contaminated and must be thrown away. If the articles are meat, it is obvious that monetary losses can be large.
It is, thus, apparent that the need exists for improved apparatus for sensing articles which are dropped from a conveyor path of a package wrapping machine to prevent potential destruction or contamination of the dropped articles as well as damage to or jamming of the wrapping machine itself.